Stentless support structure

ABSTRACT

A stentless support structure capable of being at least partly assembled in situ. The support structure comprises a braided tube that is very flexible and, when elongated, becomes very long and very small in diameter, thereby being capable of placement within a small diameter catheter. The support structure is preferably constructed of one or more thin strands of a super-elastic or shape memory material such as Nitinol. When released from the catheter, the support structure folds itself into a longitudinally compact configuration. The support structure thus gains significant strength as the number of folds increase. This radial strength obviates the need for a support stent. The support structure may include attachment points for a prosthetic valve.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.13/104,866 filed May 10, 2011 entitled Stentless Support Structure,which claims priority to U.S. Provisional Patent Application Ser. No.61/333,200 filed May 10, 2010 entitled Stentless Support Structure, bothof which are hereby incorporated by reference in their entireties.

REFERENCED DOCUMENTS

U.S. patent application Ser. No. 11/443,814 entitled Stentless SupportStructure, filed May 30, 2006 is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

There has been a significant movement toward developing and performingcardiovascular surgeries using a percutaneous approach. Through the useof one or more catheters that are introduced through, for example, thefemoral artery, tools and devices can be delivered to a desired area inthe cardiovascular system to perform many number of complicatedprocedures that normally otherwise require an invasive surgicalprocedure. Such approaches greatly reduce the trauma endured by thepatient and can significantly reduce recovery periods. The percutaneousapproach is particularly attractive as an alternative to performingopen-heart surgery.

Valve replacement surgery provides one example of an area wherepercutaneous solutions are being developed. A number of diseases resultin a thickening, and subsequent immobility or reduced mobility, of heartvalve leaflets. Such immobility also may lead to a narrowing, orstenosis, of the passageway through the valve. The increased resistanceto blood flow that a stenosed valve presents can eventually lead toheart failure and ultimately death.

Treating valve stenosis or regurgitation has heretofore involvedcomplete removal of the existing native valve through an open-heartprocedure followed by the implantation of a prosthetic valve. Naturally,this is a heavily invasive procedure and inflicts great trauma on thebody leading usually to great discomfort and considerable recovery time.It is also a sophisticated procedure that requires great expertise andtalent to perform.

Historically, such valve replacement surgery has been performed usingtraditional open-heart surgery where the chest is opened, the heartstopped, the patient placed on cardiopulmonary bypass, the native valveexcised and the replacement valve attached. A proposed percutaneousvalve replacement alternative method on the other hand, is disclosed inU.S. Pat. No. 6,168,614 (the entire contents of which are herebyincorporated by reference) issued to Andersen et al. In this patent, theprosthetic valve is mounted on a stent that is collapsed to a size thatfits within a catheter. The catheter is then inserted into the patient'svasculature and moved so as to position the collapsed stent at thelocation of the native valve. A deployment mechanism is activated thatexpands the stent containing the replacement valve against the valvecusps. The expanded structure includes a stent configured to have avalve shape with valve leaflet supports begins to take on the functionof the native valve. As a result, a full valve replacement has beenachieved but at a significantly reduced physical impact to the patient.

However, this approach has decided shortcomings. One particular drawbackwith the percutaneous approach disclosed in the Andersen '614 patent isthe difficulty in preventing leakage around the perimeter of the newvalve after implantation. Since the tissue of the native valve remainswithin the lumen, there is a strong likelihood that the commissuraljunctions and fusion points of the valve tissue (as pushed apart andfixed by the stent) will make sealing around the prosthetic valvedifficult. In practice, this has often led to severe leakage of bloodaround the stent apparatus.

Other drawbacks of the Andersen '614 approach pertain to its reliance onstents as support scaffolding for the prosthetic valve. First, stentscan create emboli when they expand. Second, stents are typically noteffective at trapping the emboli they dislodge, either during or afterdeployment. Third, stents do not typically conform to the features ofthe native lumen in which they are placed, making a prosthetic valvehoused within a stent subject to paravalvular leakage. Fourth, stentsare subject to a tradeoff between strength and compressibility. Fifth,stents cannot be retrieved once deployed. Sixth, the inclusion of thevalve within the stent necessarily increases the collapsed diameter ofthe stent-valve complex and increases the caliber of the material thatmust be delivered into the vasculature.

As to the first drawback, stents usually fall into one of twocategories: self-expanding stents and expandable stents. Self-expandingstents are compressed when loaded into a catheter and expand to theiroriginal, non-compressed size when released from the catheter. These aretypically made of Nitinol. Balloon expandable stents are loaded into acatheter in a compressed but relaxed state. These are typically madefrom stainless steel or other malleable metals. A balloon is placedwithin the stent. Upon deployment, the catheter is retracted and theballoon inflated, thereby expanding the stent to a desired size. Both ofthese stent types exhibit significant force upon expansion. The force isusually strong enough to crack or pop thrombosis, thereby causing piecesof atherosclerotic plaque to dislodge and become emboli. If the stent isbeing implanted to treat a stenosed vessel, a certain degree of suchexpansion is desirable. However, if the stent is merely being implantedto displace native valves, less force may be desirable to reduce thechance of creating emboli.

As to the second drawback, if emboli are created, expanded stentsusually have members that are too spaced apart to be effective to trapany dislodged material. Often, secondary precautions must be takenincluding the use of nets and irrigation ports.

The third drawback is due to the relative inflexibility of stents.Stents typically rely on the elastic nature of the native vessel toconform around the stent. Stents used to open a restricted vessel do notrequire a seal between the vessel and the stent. However, when using astent to displace native valves and house a prosthetic valve, a sealbetween the stent and the vessel is necessary to prevent paravalvularleakage. Due to the non-conforming nature of stents, this seal is hardto achieve, especially when displacing stenosed valve leaflets.

The fourth drawback is the tradeoff between compressibility andstrength. Stents are made stronger or larger by manufacturing them withthicker members. Stronger stents are thus not as compressible as weakerstents. Most stents suitable for use in a valve are not compressibleenough to be placed in a small diameter catheter, such as a 20Fr, 16Fror even 14Fr catheter. Larger delivery catheters are more difficult tomaneuver to a target area and also result in more trauma to the patient.

The fifth drawback of stents is that they are not easily retrievable.Once deployed, a stent may not be recompressed and drawn back into thecatheter for repositioning due to the non-elastic deformation (stainlesssteel) or the radial force required to maintain the stent in place(Nitinol). Thus, if a physician is unsatisfied with the deployedlocation or orientation of a stent, there is little he or she can do tocorrect the problem.

The sixth drawback listed above is that the combination of the valvewithin the stent greatly increases the size of the system required todeliver the prosthetic device. As a result, the size of the entry holeinto the vasculature is large and often precludes therapy, particularlyin children, smaller adults or patients with pre-existing vasculardisease.

It is thus an object of the present invention to address thesedrawbacks. Specifically, it is an object of the invention to provide asupport structure that expands gently, with gradual force, therebyminimizing the generation of emboli.

It is further an object of the invention to provide a support structurethat traps any emboli generated, thereby preventing the emboli fromcausing damage downstream.

It is yet another object of the invention to provide a support structurethat conforms to the features of the lumen in which it is beingdeployed, thereby preventing paravalvular leakage.

It is still another object of the invention to provide a strong supportstructure capable of being deployed from a very small diameter catheter.

It is further an object of the invention to provide a support structurethat is capable of being retracted back into a delivery catheter andredeployed therefrom.

It is another object of the invention to provide a device that isdelivered with the valve distinctly separated from the inside diameterof the final configuration of the support structure in order to reducethe amount of space required to deliver the device within thevasculature of the patient.

BRIEF SUMMARY OF THE INVENTION

The present invention accomplishes the aforementioned objects byproviding a tubular mesh support structure for a native lumen that iscapable of being delivered via a very small diameter delivery catheter.The tubular mesh is formed one or more fine strands braided togetherinto an elongate tube. The strands may be fibrous, non-fibrous,multifilament, or monofilament. The strands exhibit shape memory suchthat the elongate tube may be formed into a desired folded shape, thenstretched out into a very small diameter, elongated configuration. Thesmall diameter, elongated configuration makes a very small diameterdelivery catheter possible.

Upon deployment, the elongated tube is slowly pushed out of the deliverycatheter, where it gradually regains its folded, constructedconfiguration. The tube conforms to the internal geometries of thetarget vessel. In addition, the braid effectively traps all emboli thatmay be released from the vessel walls.

As the tube continues to be pushed from the delivery catheter, it beginsto fold in upon itself as it regains its constructed configuration. Asit folds in upon itself, the forces exerted by each layer add together,making the structure incrementally stronger. Thus, varying levels ofstrength may be achieved without changing the elongated diameter of thedevice.

Using this folded tube, the valve can be attached such that the valve orother structure (such as a filter) in its elongated configuration withinthe delivery catheter does not reside within the elongated tube, but ondeployment can be positioned in, above or below the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of the presentinvention in an elongate configuration;

FIG. 2 is a side view of a preferred embodiment of the presentinvention;

FIGS. 3-12 are a sequence of perspective views of a preferred embodimentof the present invention being deployed from a delivery catheter;

FIG. 13 is a perspective view of a preferred embodiment of the presentinvention;

FIG. 14 is a first end view of the preferred embodiment of FIG. 13;

FIG. 15 is a second end view of the preferred embodiment of FIG. 13;

FIG. 16 is a side view of a preferred embodiment of the presentinvention;

FIG. 17 is a second end view of the preferred embodiment of FIG. 16;

FIG. 18 is a first end view of the preferred embodiment of FIG. 16;

FIG. 19 is a side view of a preferred embodiment of the presentinvention;

FIG. 20 is a first end view of the preferred embodiment of FIG. 19;

FIG. 21 is a second end view of the preferred embodiment of FIG. 19;

FIG. 22 is a partial perspective view of a preferred embodiment of thepresent invention;

FIG. 23 is a partial perspective view of a preferred embodiment of thepresent invention;

FIG. 24 is a perspective view of a preferred embodiment of the presentinvention;

FIG. 25 is a side elevation of the embodiment of FIG. 24;

FIG. 26 is a second end view of the embodiment of FIG. 24;

FIGS. 27-36 are a sequence of perspective views of a preferredembodiment of the present invention being deployed from a deliverycatheter against a clear plastic tube representing a native valve;

FIG. 37 is a side elevation view of a preferred embodiment of thepresent invention;

FIG. 38 is an end view of a downstream side of the embodiment of FIG.37;

FIG. 39 is an end view of an upstream side of the embodiment of FIG. 37;

FIG. 40 is a side view of a transapical delivery procedure of apreferred embodiment of the present invention;

FIG. 41 is a cross sectional view of a heart during the transapicaldelivery procedure of FIG. 40;

FIG. 42 is a cross sectional view of a heart during the transapicaldelivery procedure of FIG. 40;

FIG. 43 is a magnified view of a support structure during thetransapical delivery procedure of FIG. 40;

FIG. 44 is a magnified view of a support structure during thetransapical delivery procedure of FIGS. 40;

FIG. 45 is a magnified view of a support structure during thetransapical delivery procedure of FIG. 40; and,

FIG. 46 is a cross sectional view of a heart during the transapicaldelivery procedure of FIG. 40.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the Figures and first to FIG. 1, there is shown astentless support structure 10 of the present invention in an extendedconfiguration. The valve support 10 includes a first end 12, a secondend 14 and an elongate tubular body 16 extending between the first end12 and the second end 14.

The elongate tubular body 16 is preferably formed from one or aplurality of braided strands 18. The braided strands 18 are strands of asuper-elastic or shape memory material such as Nitinol. The strands arebraided to form a tube having a central lumen 20 passing therethrough.

In one embodiment, the tubular body 16 is folded in half upon itselfsuch that the second end 14 becomes a folded end and the first end 12includes a plurality of unbraided strands. The tubular body 16 is thustwo-ply. The unbraided strands of the first end 12 are gathered andjoined together to form a plurality of gathered ends 22. The gatheredends 22 may be used as commissural points for attaching a prostheticvalve to the support structure 10. (See, e.g. FIG. 2). Alternatively, asshown in FIG. 1, the gathered ends 22 may be used as attachment pointsfor a wireform 24 defining a plurality of commissural points 26.

Notably, the commissural points 26 are positioned such that, when avalve is attached to the support structure in the extendedconfiguration, the valve is longitudinally juxtaposed with the supportstructure rather than being located within the support structure. Thisjuxtaposition allows the support structure 10 and valve to be packedinto a very small catheter without damaging the delicate valve. Thislongitudinal juxtaposition may be maintained when the support structureassumes a folded or constructed configuration (see FIG. 19 for example),or the valve may become folded within the support structure.

FIGS. 3-6 show the second end 14 emerging from the catheter 28 to exposea first layer 30. In FIG. 7, the first layer 30 is completely exposedand has assumed its constructed configuration. Notably, the first layer30 contracts longitudinally when fully deployed. Also shown in FIG. 7 isa second layer 32 beginning to emerge from the catheter 28. As thesecond layer exits the catheter, the pre-set super-elastic fold invertsthe mesh, such that a second, inner layer is formed within the firstouter layer. Alternatively, the first layer can be deployed against thewall of the vascular structure (such as an artery, vein, valve or heartmuscle). As the second layer exits the catheter, the physician can aidinversion of the mesh my advancing the deployment system. In anotherembodiment, the mesh support structure can be advanced in thevasculature such that it is deployed in a reverse direction (such asdeployment through the apex of the heart ventricle or from the venoussystem), where the mesh inversion occurs as a result of pulling orretracting the deployment system.

In FIG. 10, the second layer 32 is fully deployed and the third layer 34is fully exposed, but has not yet been inverted. Retracting the catheter28, relative to the device 10, while advancing the catheter 28 slightly,relative to the target site, causes the third layer 34 to “pop”inwardly, thereby inverting itself against an inside surface of thesecond layer 32, as seen in FIG. 11.

In FIG. 12, additional material has been ejected from the catheter 28such that the third layer 34 is fully expanded against the second layer.One skilled in the art will realize that numerous additional layers canbe achieved in this manner, and that each layer adds additional radialstrength to the resulting support structure 10.

Throughout the deployment process, the stentless support structure 10emerges from the delivery catheter 28 gradually. This characteristicalso allows the structure 10 to be pulled back into the deliverycatheter 28, in the event that it is desired to relocate the supportstructure 10. Doing so causes the support structure 10 to reacquire itsextended configuration.

Having described the mechanics of building a support structure in situ,attention can now be turned to various embodiments made possible by thepresent invention. FIGS. 13-15 show a support structure 10 having manylayers 38 and a first end 12 with numerous gathered ends 22 formed fromunbraided strands. Some of the gathered ends 22 are attached to awireform 24 having three commissural points 26. A prosthetic valve 36,either harvested or manufactured, is attached to the wireform 24. FIG.15 shows the internal lumen 20 of the support structure 10.

FIGS. 16-18 show a support structure 10 having fewer layers 38 and awireform 24 with a prosthetic valve 36 attached thereto. The first end12 (hidden), to which the wireform 24 is attached, has been preformed tofold inwardly upon deployment. Thus, the wireform 24 and prostheticvalve 36, is located in the inner lumen 20 of the support structure 10when the support structure 10 is in a constructed configuration.

FIGS. 19-21 show a support structure 10 with several layers 38 and afirst end 12 preformed to have a smaller diameter than the rest of thelayers and the second end 14, which is folded. The terminal ends of thebraided strands at the first end 12 have not been formed into gatheredends. Rather, the wireform 24 is attached to the braids. The prostheticvalve 36 is attached to the wireform 24 and has skirting tissue 40,which is placed around the outside of the end 12. The skirting tissue 40may be adhered to the first end 12.

FIG. 22 shows a stentless support structure 10 with a folded end 14,which has been folded back on itself, and a material 42 trapped betweenthe two layers of the fold. The material 42 is provided to furtherimprove the paravalvular leak prevention and embolic trappingcharacteristics of the stentless support structure 10. The material 42could consist of a non-woven material, woven or braided fabric, apolymer or other material.

FIG. 23 shows a stentless support structure 10 that includes a fiber 44that is larger than the rest of the strands comprising the supportstructure 10. Thus, FIG. 23 demonstrates that strands of different sizesmay be used in the braided support structure 10 without significantlyaffecting the minimum delivery size of the device. Different sizedstrands may be used in order to improve strength, provide stiffness,create valve attachment points, provide radiopaque markers, and thelike.

FIGS. 24-26 show a stentless support structure 10 that has a first end12 that has had the unbraided strands trimmed such that they do notextend past the first end 12 of the folded structure 10. This embodimentmay be used to create, preserve or enlarge a lumen. A prosthetic valvemay or may not be attached to this embodiment.

Turning now to FIGS. 27-36, a deployment sequence of a preferredembodiment of the stentless support structure 10 is shown whereby aclear piece of tubing 46 is used to demonstrate a targeted location of anative vessel, such as a native valve. In FIG. 27, the delivery catheter28 is advanced beyond the targeted valve 46 and the stentless support 10is starting to be ejected from the catheter 28.

In FIG. 28, enough of the stentless support 10 has been ejected that thesecond, folded end 14 has begun to curl back on itself slightly, forminga cuff 48. In FIG. 29, the cuff 48 is more visible and has assumed itsfull, deployed shape. The cuff 48 acts as a catch that a physician canuse to visually or tactilely locate the targeted valve 46 and seat thestentless support 10 thereagainst. The cuff also acts to ensure theentire native lumen through the targeted valve 46 is now being filteredby the support 10. Unlike balloon expandable stents, blood flow is notsignificantly inhibited by the deployment of the stentless supportstructure 10. Also shown in FIG. 29 is that the first layer 30 has beenfully ejected from the catheter 28, as has much of the second layer 32.The first layer 30, being very flexible prior to reinforcement bysubsequent layers, is able to conform to any shape of the targetedvessel. The second layer 32 has not yet inverted itself into the firstlayer 30.

In FIG. 30, the first layer 30 is deployed, the cuff 48 is actingagainst the valve 46, and the second layer 32 has been inverted. In FIG.31, material forming the third layer 34 is ejected from the catheter 28but the third layer 34 has not yet inverted.

In FIGS. 32-33, the catheter 28 is being advanced to allow the thirdlayer 34 to invert into the second layer 32. The angle of FIG. 32 showsthe relatively low profile created by the first and second layers 30 and32, and how little resistance to blood flow is presented by the supportstructure 10.

In FIG. 34, the first end 12 has emerged from the catheter 12, and thegathered ends 22 are showing. A wireform 24 is attached to some of thegathered ends 22 and is nearly completely deployed from the deliverycatheter 28. In FIGS. 35-36, the support structure 10 has beencompletely released from the catheter 28. FIG. 36 shows the size of thelumen 20 of the support structure 10.

FIGS. 37-39 show a preferred embodiment 100 of the present inventionincluding a mesh support structure 102, a wireform 104 and a valve 106.The support structure 102 differs slightly from support structure 10,described previously, as it is constructed from a two individual wires108. Upon completion of the braiding process, the two free ends of thewire are spliced together. As such, there are no free wire ends and thestructure can be loaded into a delivery catheter in a single-ply state(not shown). In the deployed state shown in the Figures, the supportstructure 102 is folded once to form a two-ply device.

The support structure 102 is preferably formed of a memory alloy such asNitinol. The single-wire construction allows the device to be compressedinto an extremely small catheter, such as one sized 16Fr or smaller.Though the support structure gains rigidity by the two-ply deployedconfiguration, radial strength is a function of a several factors andcan thus be varied widely.

First, as with the other embodiments, radial strength may be increasedby incorporating more folds or layers into the deployed configuration ofthe support structure 102. The three-ply configuration shown in FIGS.37-39 is the most preferred configuration because it only has to befolded in on itself twice, making deployment less complicated.

Second, strength may be increased by using a heavier wire. Because thesupport structure 102 is made from a single-wire, and can thus be loadedinto a catheter in a single-ply configuration, a larger diameter wiremay be used while maintaining a small diameter elongated profile.Support structures 102 have been constructed according to the presentinvention using single wires having diameters between 0.005 and 0.010inches in diameter. Preferably, the diameter of the wire is between0.007 and 0.008 inches.

Third, strength may be increased by increasing the braid density. Atighter braid will result in a stronger support.

Fourth, the strength may be increased by altering the heat settingparameters. Super-elastic and shape memory alloys, such as Nitinol,attain their deployed shape within the vasculature by being heat set.The wires are held in a desired configuration and heated to apredetermined temperature for a predetermined period of time. After thewires cool, they become set to the new configuration. If the wires arelater disfigured, they will return to the set configuration upon heatingor simply releasing the wires. The force with which a super-elastic orshape memory alloy returns to a set configuration can be increased bymodifying the temperature at which the configuration is set, or bymodifying the period of time the alloy is maintained at the elevatedsetting temperature. For example, good results have been attainedsetting a Nitinol support structure of the present invention at 530° C.for 7 minutes. Stiffer support structures can be made using the sameNitinol wire by setting the structure at a temperature other than 530°C. or by setting the structure at 530° C. for a time other than 7minutes, or both.

The device 100 includes a wireform 104, to which a valve 106 isattached. The wireform 104 form commissural points separated by arcuateportions 110. The arcuate portions 110 are attached to an inside surfaceof the support structure 102. The commissural points 109 facilitatenatural and efficient opening and closing of the valve 106.Alternatively, the valve commissural points can be attached to an outersurface of the support structure (not shown).

The valve 106 may be any form of prosthetic or harvested biologicalvalve. Preferably, as shown in the Figures, the valve 106 is a valvehaving three leaflets. The valve 106 is sutured or otherwise attached tothe wireform 104. Preferably, the valve 106 is cut or constructed toinclude a skirt portion 112 which continues along the length of thesupport structure 102 in its deployed configuration.

FIGS. 40-46 illustrate the operation of another delivery techniqueaccording to the present invention in which the support structure 10replaces a diseased valve. However, instead of advancing an elongatedcatheter through a remote vessel to reach a heart valve (e.g., throughthe femoral artery to the aortic valve), a relatively short deliverycatheter 200 is advanced through the chest and heart wall to reach adesired native valve. Once the native valve is reached, the user candeploy and shape the support structure 10 in a manner similar to thepreviously described methods.

Turning now to FIG. 40, a mini thoracotomy is performed on a patient,opening up a small passage in the chest between the ribs. A path iscreated from the chest incision, through the intervening tissue layers(e.g., cardial sacks) to the heart 204. A heart bypass procedure mayalso be performed to reduce any complications otherwise caused bycreating an incision in the heart 204.

Referring to FIG. 41, an incision 207 is created near the lower apex 201of the heart 204 (i.e., a transapical approach into the heart) to accessthe left ventricle 203 and ultimately the native aortic valve 208.Preferably, purse-string sutures 202 are sutured around the incision 207shortly after its creation to minimize blood loss that may otherwiseoccur from the beating heart 204.

A guidewire (not shown) is advanced into the chest, through the incision207 into the heart 204. In the present example, a distal end of theguidewire is advanced into the left ventricle 206 and through the nativeaortic valve 208. As seen in FIGS. 40 and 41, the delivery catheter 200is slid over the guidewire, through the chest, into the incision 207 andthrough the left aortic valve 208.

Referring to FIG. 42, the support structure 10 is oriented within thecatheter 200 to have the first end 12 in a distal position and thesecond end 14 in a proximal position, allowing the first end 12 of thesupport structure 10 to be released first into the aorta 210. In thisrespect, the prosthetic valve 36 (not shown in FIG. 42) is oriented toopen as blood flow passes from the left ventricle 206 into the aorta 210during a heart beat.

It should be noted, however, that the support structure 10 may bepositioned within the delivery catheter 200 to initially deploy thefirst end 12 or the second end 14. The desired orientation will depend,in part, on the direction from which the delivery catheter 200approaches the native valve and therefore the location where thedelivery catheter enters the heart 204.

Referring to FIGS. 42 and 43 of the present example, the supportstructure 10 is pushed out of the delivery catheter 200 so that thefirst end 12 deploys into the aorta 210. The delivery catheter 200 ismoved proximally back through the valve 208 as the support structure 10continues to be pushed out of the distal end of the catheter.

Turning to FIG. 44, the support structure 10 is seen fully deployed sothat the second end 14 of the support structure 10 is positioned throughthe aortic valve 208 and within the left ventricle 206. As seen in thisfigure, the delivery catheter 200 includes a pull wire 220 positionedthrough the delivery catheter 200 and within the support structure 10.The pull wire 220 includes a distal end coupled to the first end 12(i.e., the distal end) of the support structure 10 and a proximal end ofthe pull wire 220 which is accessible to the user at a proximal end ofthe delivery catheter 200.

Once the support structure 10 is deployed to a desired position, such asthat seen in FIG. 44, the user moves the pull wire 220 in a proximaldirection, causing the first end 12 of the support structure 10 toinvert or fold back on itself. FIGS. 45 and 46 illustrate an exampleinverted conformation of the support structure 10 in which the first end12 moves within the center passage of the support structure 10.

When the user is satisfied that the support structure 10 has achieved adesired shape, the pull wire 220 is disconnected from the first end 12of the support structure 10. The pull wire 220 may include differentselectively releasable arrangements that allow the user to disconnect oruncouple the distal end of the pull wire 220 at a desired time. Forexample, the pull wire 220 may include selectively releasable jaws suchas those seen on the connecting members in the U.S. ProvisionalApplications No. 60/827373 entitled Delivery Tool For PercutaneousDelivery Of A Prosthesis, filed Sep. 28, 2006; the contents of which arehereby incorporated by reference. Alternately, the pull wire 220 mayinclude hooks or detachable adhesives to release the pull wire 220 fromthe support structure 10.

Finally, as seen in FIG. 46, the user removes the delivery catheter 200and the guidewire from the heart 204 and fully closes the incision 207with the purse string sutures 202. Any remaining incisions in thepatient's chest are closed and the procedure is complete.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A method of delivering a support structurecomprising: navigating to a target location, a support structure havingtwo unfolded axially-spaced preformed folds defining a distal portion, amiddle portion, and a proximal portion; positioning said supportstructure within the target location; allowing said two unfoldedaxially-spaced preformed folds to assume folded configurations, therebycausing said middle portion to invert such that said distal portion ispulled into said proximal portion.
 2. The method of claim 1 whereinallowing said two unfolded axially-spaced preformed folds to assumefolded configurations comprises pulling said distal portion toward saidproximal portion.
 3. The method of claim 1 wherein navigating to atarget location comprises navigating a catheter containing said supportstructure through the apex of a heart, through the left ventricle andpositioning a distal end of the catheter within or near the aortic valveof the heart.
 4. The method of claim 1 wherein positioning said supportstructure within a target location comprises pushing said distal portionout of a delivery catheter distal of said target location.
 5. The methodof claim 1 wherein allowing said two unfolded axially-spaced preformedfolds to assume folded configurations, thereby causing said middleportion to invert such that said distal portion is pulled into saidproximal portion comprises allowing said two unfolded axially-spacedpreformed folds to assume folded configurations, thereby causing saidmiddle portion to invert such that said distal portion is pulled intosaid proximal portion, said proximal portion being located at saidtarget location.
 6. The method of claim 1 wherein positioning saidsupport structure within a target location comprises sliding a deliverycatheter containing said support structure over a guidewire leading tosaid target location.
 7. The method of claim 1 wherein allowing said twounfolded axially-spaced preformed folds to assume folded configurationscomprises preventing proximal movement of said support structure with acatheter while pulling proximally with a pull wire.
 8. The method ofclaim 7 wherein preventing proximal movement of said support structurewith a catheter while pulling proximally with a pull wire comprisesacting on a distal portion of said support structure with a pull wirethat passes through at least a portion of said support structure.
 9. Asystem for implanting an invertible support structure comprising: animplantable valve assembly including a proximal portion, a middleportion, and a distal portion, the distal portion at least partiallycomprising a valve mechanism; a delivery catheter configured to containthe implantable valve assembly in an unfolded, elongated state; aninversion mechanism that causes the middle portion to inwardly invert,thereby drawing the distal portion into the proximal portion.
 10. Thesystem of claim 9 wherein said inversion mechanism comprises a pullwire.
 11. The system of claim 9 wherein said implantable valve assemblycomprises a mesh tube constructed of memory metal.
 12. The system ofclaim 11 wherein said inversion mechanism comprises a preformed fold insaid mesh tube that regains a folded state when released from saiddelivery catheter.
 13. The delivery device of claim 11 wherein saidinversion mechanism is releasably connected to said mesh tube distal ofa preformed fold formed in said support structure.
 14. The deliverydevice of claim 13 wherein said inversion mechanism is releasablyconnected to a distal end of said mesh tube.
 15. The delivery device ofclaim 9 wherein said valve mechanism comprises a wireform having adistal end and a proximal end, the proximal end attached to a distal endof the middle portion.
 16. The delivery device of claim 11 wherein saidmesh tube comprises two axially spaced preformed folds.
 17. The deliverydevice of claim 16 wherein said inversion mechanism is releasablyconnected to said mesh tube near a distal-most preformed fold.
 18. Thedelivery device of claim 16 wherein said preformed folds cause saidinvertible, implantable support structure to form a folded structure,upon inversion, having three plies in at some point along an axiallength of said folded structure.
 19. A prosthetic valve assemblycomprising: a distal portion, a middle portion and a proximal portion;said proximal portion separated from said middle portion by aninward-facing preformed fold; said distal portion including a prostheticvalve; wherein at least said proximal portion and said middle portioncomprise a mesh tube constructed of memory metal; wherein, whenreleased, said inward-facing preformed fold resumes a foldedconfiguration that draws said distal portion into said middle portion.20. The prosthetic valve assembly of claim 19 wherein said distalportion comprises a distal end of said mesh tube and is separated fromsaid proximal portion by an outward-facing preformed fold in said meshtube that, when released, resumes a folded configuration that preventssaid distal portion from inverting with said middle portion.